Airlaid composite sheet material
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Solution Overview
Problem
Conventional absorbent articles face issues with rapid fluid acquisition in the z-direction but inadequate lateral fluid distribution, leading to localized fluid exposure and discomfort for the wearer.
Innovation Solution
A composite sheet material comprising a fluid acquisition layer and an airlaid layer with a blend of cellulose and non-cellulose staple fibers, thermally bonded without adhesives, providing a density gradient for efficient fluid transport and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional AQDL materials are used, then rapid fluid acquisition in the z-direction is achieved, but lateral fluid distribution in the x and y directions is inadequate
Solution Approach 1:
The AQDL is divided into multiple discrete airlaid layers (first, second, and third layers) with different fiber compositions and densities. Each layer segments the fluid transport function, with upper layers focusing on rapid acquisition and lower layers emphasizing lateral distribution, thereby resolving the contradiction between speed and distribution quantity.
Solution Approach 2:
Different regions of the AQDL are assigned different fiber blend ratios and densities. The upper airlaid layers contain higher synthetic fiber content for rapid vertical transport, while the lower airlaid layer increases cellulose content to enhance lateral wicking and distribution, creating local quality variations that simultaneously achieve both rapid acquisition and adequate distribution.
2Ease of manufacture
If conventional single-layer AQDL structures are used, then manufacturing simplicity is maintained, but fluid distribution uniformity deteriorates
Solution Approach 1:
The AQDL is constructed as multiple discrete airlaid layers that can be manufactured separately using standard airlaid processes, then bonded together. This segmentation allows each layer to be optimized for specific functions while maintaining compatibility with existing manufacturing equipment and processes, achieving both manufacturing feasibility and improved fluid distribution uniformity.
Solution Approach 2:
The invention uses composite material construction with multiple airlaid layers having different fiber compositions (cellulose and synthetic fiber blends) and densities. These composite layers are thermally bonded to create a unified structure that achieves superior fluid distribution uniformity while remaining manufacturable through conventional thermal bonding processes.
3Strength
If adhesive bonding is used to combine layers, then layer bonding strength is improved, but material complexity and processing steps increase
Solution Approach 1:
The airlaid layers are equipped with thermal bonding capabilities through their fiber composition, allowing them to bond to each other through heat application alone without requiring adhesive materials. This self-service bonding mechanism eliminates the need for separate adhesive application and curing steps, maintaining bonding strength while reducing processing complexity.
Solution Approach 2:
The adhesive bonding function is extracted and replaced by direct thermal bonding between the airlaid layers. By removing the adhesive component entirely and relying on the thermal bonding properties of the fiber materials themselves, the invention achieves layer bonding strength without the added complexity of adhesive materials and associated processing steps.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composite sheet material enhances fluid distribution and absorption, reducing surface stains, improving comfort, and maintaining anti-reverse osmosis performance, while being softer and fluffier than prior art materials.
Implementation Method 1
The layers are thermally bonded without adhesives
Implementation Method 2
rapid transport (also referred to herein as flash permeation) transports the fluid in the z-direction from the top sheet to the absorbent core
Implementation Method 3
rapid transport (also referred to herein as flash permeation) transports the fluid
Data Source
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AI summary
Provided is a composite sheet that is particularly useful as an AQDL component in absorbent articles. The composite sheet includes a fluid acquisition component and an airlaid component. The airlaid component may include one or more airlaid layers that are successively formed overlying each other. Each of the airlaid layers are adjacent to, and in direct contact with, immediately adjacent layers of the airlaid component so that adjacent layers are in fluid communication with respect to each other. The fluid acquisition component includes a nonwoven fabric comprising a carded nonwoven fabric comprised of a plurality of staple fibers that are air through bonded to each other to form a coherent nonwoven fabric. The airlaid layer(s) include a blend of cellulose and non-cellulose staple fibers. The staple fibers may be bicomponent fibers having a polyethyelene sheath and a polypropylene or polyethylene terephthalate core, and mixtures of such fibers.